CAOSA-extracted lignin improves enzymatic hydrolysis of cellulose

The conversion of biomass into sugar platform compounds is very important for the biorefinery industry. Pretreatment is essential to the biomass of the sugar platform, however, the lignin obtained by pretreatment, as a key part of lignocellulose, generally has a passive effect on the enzymatic hydrolysis of cellulose into sugars. In this study, p-TsOH (p-toluenesulfonic acid), DES (Deep eutectic solvent) and CAOSA (cooking with active oxygen and solid alkali) pretreatment ways were used to fraction lignin from bamboo biomass. After CAOSA treatment, the hydrolysis efficiency of the pulp was 95.57%. Moreover, the effect of different treatment methods on lignin properties was studied and the promotion effect of lignin was investigated by adding it to the cellulose enzymatic hydrolysis system. In this work, the results showed that CAOSA-extracted lignin with lower Đ (1.31–1.25) had a better adsorption effect on the enzyme protein. p-TsOH-extracted lignin with a larger S/G ratio (0.70) enhanced the hydrophobicity of lignin causing the inhibition of enzymatic hydrolysis. In addition, the presence of -COOHs in lignin could reduce its inhibitory effect on cellulose saccharification.